1. Field of the Invention
The present invention relates generally an edge wheel for a substrate used in wafer cleaning and other operations.
2. Description of the Related Art
Silicon wafers and other substrate materials used in integrated circuit manufacturing must be planarized and polished to meet stringent surface flatness requirements. One common technique for planarizaiton is known as chemical-mechanical planarization/polishing or CMP. CMP is essentially mechanical polishing in which the slurry used is also an etchant for the surface to be polished. After CMP processing, contaminated substrates are cleaned. In one step of cleaning, the surfaces of the substrate are brushed while a cleaning fluid is applied. To dry the substrate, it is supported by a plurality of edge wheels at the edges of the wafer and spun. Other methods of drying in which the wafer is supported by edge wheels are feasible as well. The spinning causes most of the fluid to fly off the substrate. However, due to surface tension, some fluid tends to remain at the edges. In addition, a meniscus can form at the interface of the edge wheels and the substrate. And finally, some liquid may remain on the edge wheel and re-wet the substrate as it spins around.
It is possible to remove some fluid by applying a suction at the edge of the wafer or at the edge of the wheel, but heretofore, there has been no way of effectively removing fluid at the interface of the edge wheel and the substrate.